Method for treating surface of substrate and surface treatment composition used for the same

ABSTRACT

A method for treating the surface of a substrate with a surface treatment composition, wherein the surface treatment composition comprises a liquid medium containing a complexing agent as a metal deposition preventive, the complexing agent comprising at least one member selected from Group A complexing agents and at least one member selected from Group B complexing agents as defined hereinafter.

TECHNICAL FIELD

[0001] The present invention relates to a surface treatment compositionand a method for treating the surface of a substrate using the same.More particularly, the present invention relates to a surface treatmentcomposition comprising a liquid medium as the main component, whichprevents a substrate surface from being contaminated with metalimpurities from the surface treatment composition and stably provides anextremely clean substrate surface, and also relates to a method fortreating the surface of a substrate by using the same. Further, thepresent invention relates to a method for supplying components for thesurface treatment composition and a method for purifying a complexingagent used for the composition.

BACKGROUND ART

[0002] In accordance with high integration of various devicesrepresented by VLSI, TFT liquid crystals and the like, cleanlinesslevels of substrate surfaces used for these devices are demanded to behigher and higher. Contaminations with various materials disturb toachieve higher cleanliness, and among the contaminations, a metalliccontamination particularly deteriorates electric properties of a device,and it is therefore necessary to utmostly lower a metal impurityconcentration on a substrate surface for forming a device in order toprevent the above-mentioned deterioration. For this purpose, it isgenerally conducted to clean a substrate surface with a cleaning agent.

[0003] Heretofore, for this type cleaning agent, there are generallyused water, electrolyzed ionic water, acid, alkali, oxidizing agent,surfactant aqueous solution or organic solvents and the like. Thecleaning agent is demanded not only to have excellent cleaningperformances but also to have an impurity concentration of such anextremely low level as to prevent a substrate from being contaminatedwith a metal impurity from the cleaning agent. In order to satisfy thesedemands, cleaning chemicals for semiconductors are highly purified, anda metal impurity concentration in the chemicals immediately afterpurification reaches a level of hardly detectable by present analyticaltechniques.

[0004] Although an impurity in a cleaning agent is lowered to such a lowlevel as to be hardly detectable, it is still difficult to provide ahighly clean substrate surface. This is because it can not be avoidedthat a cleaning agent itself is contaminated with a metal impurityremoved from a substrate in a cleaning tank. Thus, a metal impurityseparated from a metal surface is incorporated into a cleaning agent andthe metal impurity in the contaminated cleaning agent is then depositedon a substrate (reverse contamination).

[0005] In a step of cleaning semiconductors, cleaning (SC-1 cleaning)with “ammonia+hydrogen peroxide+water” solution is widely used (see RCAReview, p 187-206, June (1970) etc.). This cleaning is usually conductedat 40-90° C., and the composition ratio of a cleaning solution usuallyused is (30 wt % aqueous ammonia):(31 wt % hydrogenperoxide):(water)=0.05:1:5 to 1:1:5. However, this cleaning method hashigh performances to efficiently remove particles and organic materials,but when metals such as Fe, Al, Zn and Ni are present even in a verysmall amount in the solution, they are deposited on a substrate surface,thus raising a problem of reverse contamination. For this purpose, inthe step of cleaning semiconductors, after cleaning with“ammonia+hydrogen peroxide+water” solution, cleaning with an acidcleaning agent such as “hydrochloric acid+hydrogen peroxide+water”solution (SC-2 cleaning) is usually conducted to remove metalcontamination on a substrate surface.

[0006] Therefore, in the cleaning step, a technique to prevent thereverse contamination has been demanded in order to stably andefficiently provide a highly clean surface.

[0007] Further, a problem of deposition of metal impurities in a liquidonto a substrate surface is generally a large problem not only in thecleaning step but also in substrate surface treatment steps using asolution such as an alkali etching step of a silicon substrate, anetching step of a silicon oxide film with dilute hydrochloric acid, andthe like. In the etching step with dilute hydrofluoric acid, when noblemetal impurities such as Cu and Au are present in the solution, they aredeposited on the silicon surface and extremely deteriorate electricproperties of devices such as carrier lifetime. Although, in the alkalietching step, when a small amount of metal impurities such as Fe and Alare present in the solution, they are easily deposited on the substratesurface and adversely affect on its quality. Thus, a technique toprevent contamination in a surface treatment step with a solution isstrongly demanded.

[0008] In order to solve these problems, there is proposed a method forpreventing metal impurities from being deposited on a substrate surfaceby adding a complexing agent such as a chelating agent to a surfacetreatment agent to trap the metal impurities in the solution as stablewater-soluble complexes. For example, JP-A-50-158281 proposes to preventdeposition of metal impurities on a semiconductor substrate surface byadding a complexing agent such as ethylenediaminetetraacetic acid (EDTA)or ammonium cyanide to a tetraalkylammonium hydroxide aqueous solution.JP-A-3-219000 proposes a chelating agent such as catechol and Tiron,JP-A-5-275405 proposes a phosphonic acid type chelating agent or acomplexing agent such as condensed phosphoric acid and JP-A-6-163495proposes a complexing agent such as hydrazone derivative, and they arerespectively added to an alkaline cleaning solution such as“ammonia+hydrogen peroxide+water” solution to prevent metal impuritydeposition on a substrate, thereby providing a substrate surface notcontaminated with particles, organic materials and metals.

[0009] However, when these complexing agents are added, deposition of aspecific metal (such as Fe) can be prevented or a removal effect can berecognized, but there are problems that the effect of theabove-mentioned complexing agent is extremely small with regard tometals other than Fe (such as Al) which easily contaminate a treatingsolution or a substrate and that the effect can not be sufficientlyachieved even by adding a large amount of complexing agents. In order tosolvent these problems, JP-A-6-216098 proposes to clean a substrate with“ammonia+hydrogen peroxide+water” cleaning solution containing achelating agent such as a phosphonic acid type chelating agent and thento rinse with a hydrofluoric acid aqueous solution of at least 1 ppm.According to this method, since the cleaning solution containing thephosphonic acid type chelating agent does not substantially reduce Alcontamination on the substrate surface, Al is removed by etching withthe hydrofluoric acid aqueous solution of at least 1 ppm at the laterstep. Thus, the effect achieved by the conventional method forpreventing metal deposition is not satisfactory, and the metalcontamination must be removed at the later stage when the substrate isrequired to be cleaner. Consequently, the number of steps must beincreased, thereby making a production cost large.

[0010] Under these circumstances, various complexing agents have beentried to be added in order to prevent a substrate surface from beingcontaminated with metal impurities from a surface treatment composition,but a satisfactory improvement can not be made and a satisfactorytechnique for preventing contamination can not be achieved up to now.

[0011] The present invention has been made to solve the above-mentionedproblems, and provides a surface treatment composition which prevents asubstrate surface from being contaminated with metal impurities from thesurface treatment composition and stably produces an extremely cleansubstrate surface, and also provides a method for treating the surfaceof a substrate by using the same.

DISCLOSURE OF THE INVENTION

[0012] According to the present invention, an effect of preventing asubstrate from being deposited with metal impurities from a surfacetreatment composition is remarkably improved by incorporating specificat least 2 completing agents as a metal deposition preventive into thesurface treatment composition.

[0013] Also, the present invention includes a surface treatmentcomposition containing only one kind of complexing agent which achievesan effect of preventing metal impurity deposition more satisfactorilythan prior arts when the metal deposition preventive to be contained inthe surface treatment composition is a specific complexing agent.

[0014] Further, the present invention includes a method for efficientlysupplying lost components of a surface treatment composition whenconducting surface treatment with the surface treatment composition anda method for purifying ethylenediaminediorthohydroxyphenylacetic acid(hereinafter sometimes referred to as EDDHA) which is one of the mostsatisfactory metal deposition preventives.

[0015] Thus, the first essential feature of the present inventionresides in a method for treating the surface of a substrate with asurface treatment composition, wherein the surface treatment compositioncomprises a liquid medium containing a completing agent as a metaldeposition preventive, the complexing agent comprising at least onemember selected from the following Group A complexing agents and atleast one member selected from the group consisting of the followingGroups B1 to B6 complexing agents:

[0016] Group A: complexing agents having an aromatic hydrocarbon ring inthe molecular structure thereof and at least one of an OH group and/oran O⁻ group bonded directly to a carbon atom constituting the ring;

[0017] Group B1: complexing agents having at least one nitrogen atom asa donor atom in the molecular structure thereof;

[0018] Group B2: complexing agents having at least one atom selectedfrom halogen, sulfur and carbon atoms as a donor atom in the molecularstructure thereof;

[0019] Group B3: complexing agents having at least one oxygen atom as adonor atom in the molecular structure thereof, but not having a carbonylgroup and a carboxyl group and not having any one of nitrogen, halogen,sulfur and carbon atoms as a donor atom;

[0020] Group B4: carboxylic acid type complexing agents having at leastone carboxyl group in the molecular structure thereof, but not havingany one of nitrogen, halogen, sulfur and carbon atoms as a donor atomand not having a carbonyl group and a hydroxyl group;

[0021] Group B5: hydroxymono- or di-carboxylic acid type complexingagents having at most 4 hydroxyl groups in the molecular structurethereof, but not having any one of nitrogen, halogen, sulfur and carbonatoms as a donor atom and not having a carbonyl group; and

[0022] Group B6: complexing agents having at least one carbonyl group inthe molecular structure thereof.

[0023] The second essential feature of the present invention resides ina method for treating the surface of a substrate with a surfacetreatment composition which contains at least one complexing agentselected from the group consisting ofethylenediaminediorthohydroxyphenylacetic acid[ethylenediamine-N,N′-bis(orthohydroxyphenylacetic acid)],2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid,diammonium 4,4′-bis(3,4-dihydroxyphenylazo)-2,2′-stilbenedisulfonate,Pyrocatechol Violet, o,o′-dihydroxyazobenzene,1′2-dihydroxy-5-nitro-1,2′-azonaphthalene-4-sulfonic acid andN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid as a metaldeposition preventive in a liquid medium.

[0024] Further, the third essential feature of the present inventionresides in a method for treating the surface of a substrate with asurface treatment composition, wherein the surface treatment compositionis a composition containing an oxidizing agent and an organic complexingagent having an OH group bonded directly to an aromatic hydrocarbongroup in a liquid medium and the concentration of the oxidizing agent isfrom 1 ppm by weight to 3 wt %.

[0025] The fourth essential feature of the present invention resides ina method for treating the surface of a substrate with an alkalinesurface treatment composition containing ammonia, water and an organiccompleting agent having a cyclic structure in the molecular structurethereof and at least one of an OH group and/or an O⁻ group bonded to acarbon atom constituting the cyclic structure as a metal depositionpreventive in a liquid medium, wherein an ammonia component evaporatedduring the surface treatment is supplied with an ammonia aqueoussolution containing the organic complexing agent.

[0026] The fifth essential feature of the present invention resides in amethod for treating the surface of a substrate with a surface treatmentcomposition, wherein the surface treatment composition is a compositionobtained by adding highly pureethylnenediaminediorthohydroxyphenylacetic acid containing at most 5 ppmof at least one metal element of Fe, Al and Zn or its ammonium salt, asa metal deposition preventive to a liquid medium, and a method forpurifying the highly pure ethylenediaminediorthohydroxyphenylacetic acidor its ammonium salt.

[0027] Hereinafter, the present invention is further described in moredetails.

[0028] The surface treatment composition used in the above-mentionedfirst invention is characterized by containing specific at least 2complexing agents as a metal deposition preventive. The specific atleast 2 complexing agents comprise at least one complexing agentselected from the following Group A and at least one complexing agentselected from the group consisting of the following Groups B1, B2, B3,B4, B5 and B6.

[0029] In the present invention, the surface treatment generally refersto cleaning, etching, polishing and coating of a substrate, and thesurface treatment composition generally refers to a surface treatingagent used for these purposes.

[0030] Group A complexing agents have an aromatic hydrocarbon ring inthe molecular structure thereof and at least one of an OH group and/oran O⁻ group bonded to a carbon atom constituting the ring. Examples ofthese complexing agents are illustrated below, but are not limitedthereto. Also, examples are illustrated by a compound having an OHgroup, but include its corresponding salt such as an ammonium salt andan alkali metal salt. Names in parenthesis [ ] after compound namesrefer to abbreviation or common names used in the present specification.

[0031] (A-1) Phenols Having Only One OH Group and Their Derivatives

[0032] Phenol, cresol, ethylphenol, t-butylphenol, methoxyphenol,salicyl alcohol, chlorophenol, aminophenol, aminocresol, amidol,p-(2-aminoethyl)phenol, salicylic acid, o-salicylanilide, naphthol,naphtholsulfonic acid, 7-amino-4-hydroxy-2-naphthalendisulfonic acid,and the like.

[0033] (A-2) Phenal Having at Least 2 OH Groups and Their Derivatives

[0034] Catechol, resorcinol, hydroquinone, 4-methylpyrocatechol,2-methylhydroquinone, pyrogallol, 1,2,5-benzenetriol,1,3,5-benzenetriol, 2-methylfluoroglucinol,2,4,6-trimethylfluoroglucinol, 1,2,3,5-benzenetetraol, benzenehexanol,Tiron, aminoresorcinol, 2,4-dihydroxybenzaldehyde,3,4-dihydroxybenzaldehyde, dihydroxyacetophenone, 3,4-dihydroxybenzoicacid, gallic acid, 2,3,4-trihydroxybenzoic acid,2,4-dihydroxy-6-methylbenzoic acid, naphthalenediol, naphthalenetriol,nitronaphthol, naphthalenetetraol, binaphthyldiol,4,5-dihydroxy-2,7-naphthalenedisulfonic acid,1,8-dihydroxy-3,6-naphthalenedisulfonic acid, 1,2,3-anthracenetriol,1,3,5-tris((2,3-dihydroxybenzoyl)aminomethyl)benzene [MECAM],1,5,10-tris(2,3-dihydroxybenzoyl)-1,5,10-triazadecane [3,4-LICAM],1,5,9-tris(2,3-dihydroxybenzoyl)-1,5,9cyclotriazatridecane[3,3,4-CYCAM], 1,3,5-tris((2,3-dihydroxybenzoyl)carbamide)benzene[TRIMCAM], entecrobactin, enancycloenterobactin and the like.

[0035] (A-3) Hydroxybenzophenones

[0036] Dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone,2,6-dihydroxy-4-methoxybenzophenone, 2,21,5,61-tetrahydroxybenzophenone,2,3′,4,4′,6-pentahydroxybenzophenone, and the like.

[0037] (A-4) Hydroxybenzanilides

[0038] o-hydroxybenzanilide, and the like.

[0039] (A-5) Hydroxyanils

[0040] Glyoxalbis(2-hydroxyanil), and the like.

[0041] (A-6) Hydroxyphenyls

[0042] Biphenyltetraol, and the like.

[0043] (A-7) Hydroxyquinones and Their Derivatives

[0044] 2,3-dihydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone,dihydroxyanthraquinone,1,2-dihydroxy-3-(aminomethyl)anthraquinone-N,N′-diacetic acid [Alizarinecomplexane], trihydroxyanthraquinone, and the like.

[0045] (A-8) Diphenyl- or Triphenyl-alkane Derivatives

[0046] Diphenylmethane-2,2′-diol, 4,4′,4″-triphenylmethanetriol,4,4′-dihydroxyfuchsone, 4,4′-dihydroxy-3-methylfuchsone, PyrocatecholViolet [PV], and the like.

[0047] (A-9) Phenol Derivatives of Alkylamines

[0048] Ethylenediaminediorthohydroxyphenylacetic acid [EDDHA],N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid [HBED],ethylenediaminedihydroxymethylphenylacetic acid [EDDHMA], and the like.

[0049] (A-10) Phenol Derivatives of Alkylethers

[0050] 3,3′-ethylenedioxydiphenol, and the like.

[0051] (A-11) Phenols Having an Azo Group and Their Derivatives

[0052] Diammonium4,4′-bis(3,4-dihydroxyphenylazo)-2,2′-stilbenedisulfonate [Stilbazo],2,8-dihydroxy-1-(8-hydroxy-3,6-disulfo-1-naphthylazo)-3,6-naphthalenedisulfonicacid, o,o′-dihydroxyazobenzene,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid[Carmagite], chlorohydroxyphenylazonaphthol,1′2-dihydroxy-6-nitro-1,2′-azonaphthalene-4-sulfonic acid [EriochromeBlack T],2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3,6-naphthalenedisulfonicacid, 5-chloro-2-hydroxy-3-(2,4-dihydroxyphenylazo)benzene sulfonic acid[Lumogalion], 2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthalicacid [NN], 1,8-dihydroxy-2-(4-sulfophenylazo)-3,6-naphthalenedisulfonicacid,1,8-dihydroxy-2,7-bi(5-chloro-2-hydroxy-3-sulfophenylazo)-3,6-naphthalenedisulfonicacid, 1,8-dihydroxy-2,7-bis(2-sulfophenylazo)-3,6-naphthalenedisulfonicacid,2-[3-(2,4-dimethylphenylaminocarboxy)-2-hydroxy-1-naphthylazo]-3-hydroxybenzenesulfonic acid,2-[3-(2,4-dimethylphenylaminocarboxy)-2-hydroxy-1-naphthylazo]phenol,and the like.

[0053] In the first invention, at least one complexing agent selectedfrom the above Group A is contained as a metal deposition preventive. Acompleting agent is selected by synthetically considering a cleaninglevel, a complexing agent cost, a chemical stability in a surfacetreatment composition and the like required for a substrate surface, andit is hard to say unconditionally which complexing agent is best.However, in respect of a metal deposition preventive effect, when thecontent of a complexing agent in a surface treatment composition isconstant, phenol derivatives of alkylamines such asethylenediaminediorthohydroxyphenylacetic acid [EDDHA] and phenolshaving at least 2 OH groups and their derivatives such as catechol andTiron are excellent and are preferably used. Also, in respect ofchemical stability, phenol derivatives of alkylamines such asethylenediaminediorthohydroxyphenylacetic acid [EDDHA] are excellent,and in respect of a production cost of a complexing agent, 8-quinolinol,catechol, Tiron and the like are excellent and are preferably used whenthese factors are considered important. Further, a complexing agenthaving not only an OH group but also a sulfonic acid group and acarboxyl group, is excellent and preferable in respect of a metaldeposition preventive effect and a chemical stability.

[0054] Examples of other complexing agents used in combination with acomplexing agent of Group A, include complexing agents of the followingGroups B1 to B6.

[0055] (Group B1) Complexing agents having at least one nitrogen atom asa donor atom in the molecular structure thereof.

[0056] (Group B2) Complexing agents having at least one atom selectedfrom halogen, sulfur and carbon atoms as a donor atom in the molecularstructure thereof.

[0057] (Group B3) Complexing agents having at least one oxygen atom as adonor atom in the molecular structure thereof, but not having a carbonylgroup and a carboxyl group and not having any one of nitrogen, halogen,sulfur and carbon atoms as a donor atom.

[0058] (Group B4) Carboxylic acid type complexing agents having at leastone carboxyl group in the molecular structure thereof, but not havingany one of nitrogen, halogen, sulfur and carbon atoms as a donor atomand not having a carbonyl group and a hydroxyl group.

[0059] (Group B5) Hydroxymono- or di-carboxylic acid type complexingagents having at most 4 hydroxyl groups in the molecular structurethereof, but not having any one of nitrogen, halogen, sulfur and carbonatoms as a donor atom and not having a carbonyl group.

[0060] (Group B6) Complexing agents having at least one carbonyl groupin the molecular structure thereof.

[0061] In the present invention, a donor atom means an atom which canprovide electrons necessary for a coordinate bond with a metal. Examplesof a coordinate group having a nitrogen atom as a donor atom in theGroup B1, include an amino group, an imino group, a nitrilo group(tertiary nitrogen atom), a thiocyanate group, a hydroxyamino group, ahydroxyimino group, a nitro group, a nitroso group, a hydrazino group, ahydrazono group, a hydrazo group, an azo group, an azoxy group, adiazonium group and an azide group. Examples of complexing agents havingthese coordinate groups are illustrated below, but are not especiallylimited thereto.

[0062] (B1-1) Monoamines

[0063] Ethylamine, isopropylamine, vinylamine, diethylamine,dipropylamine, N-methylethylamine, triethylamine, benzylamine, aniline,toluidine, ethylaniline, xylidine, thymylamine, 2,4,6-trimethylaniline,diphenylamine, N-methyldiphenylamine, biphenylylamine, benzidine,chloroaniline, nitrosoaniline, aminobenzenesulfonic acid, aminobenzoicacid, and the like.

[0064] (B1-2) Diamines and Polyamines

[0065] Ethylenediamine, propylenediamine, trimethylenediamine,hexamethylenediamine, diethylenetriamine, diaminobenzene,toluenediamine, N-methylphenylenediamine, triaminobenzene,aminodiphenylamine, diaminophenylamine, and the like.

[0066] (B1-3) Amino Alcohols

[0067] Ethanol amine, 2-amino-1-butanol, 2-amino-2-methyl-1-propanol,2-amino-2-ethyl-1,3-propanediol, 2-(ethylamino)ethanol,2,2′-iminodiethanol, dimethylethanolamine, diethylethanolamine,ethyldiethanolamine, 3-diethylamino-1,2-propanediol, triethanolamine,and the like.

[0068] (B1-4) Aminophenols

[0069] Aminophenol, p-aminophenol sulfate, (methylamino)phenol,aminoresorcinol, and the like.

[0070] (B1-5) Amino Acids

[0071] Glycine, glycineethylester, sarcosine, alanine, aminobutyricacid, norvaline, valine, isovaline, norleucine, leucine, isoleucine,serine, L-threonine, cysteine, cystine, methionine, ornithine, lysing,arginine, citrulline, asparagic acid, asparagine, glutamic acid,glutamine, p-hydroxyglutamic acid, N-acetylglycine, glycylglycine,diglycylglycine, phenylalanine, tyrosine, L-thyroxine, N-phenylglycine,N-benzoylglycine, and the like.

[0072] (B1-6) Iminocarboxylic Acids

[0073] Iminodiacetic acid, nitrilotriacetic acid, nitrilotripropionicacid, ethylenediaminediacetic acid [EDDA], ethylenediaminetetraaceticacid [EDTA], hydroxyethylethylenediaminetetraacetic acid [EDTA-OH],trans-1,2-diaminocyclohexanetetraacetic acid [CyDTA],dihydroxyethylglycine [DHGE], diaminopropanoltetraacetic acid [DPTA-OH],diethylenetriaminepentaacetic acid [DTPA],ethylenediaminedipropiondiacetic acid [EDDP], glycol etherdiaminetetraacetic acid [GEDTA], 1,6-hexamethylenediaminetetraaceticacid [HDTA], hydroxyethyliminodiacetic acid [HIDA], methylEDTA(diaminopropanetetraacetic acid), triethylenetetraminehexaacetic acid[TTHA], 3,3′-dimethoxybenzidine-N,N,N′N′-tetraacetic acid, and the like.

[0074] (B1-7) Iminophosphonic Acids

[0075] Ethylenediamine-N,N′-bis(methylenephosphonic acid) [EDDPO],ethylenediaminetetrakis(methylenephosphonic acid) [EDTPO],nitrilotris(methylenephosphonic acid) [NTPO],diethylenetriaminepenta(methylenephosphonic acid) [ETTPO],propylenediaminetetra(methylenephosphonic acid) [PDTMP] and the like.

[0076] (B1-8) Heterocyclic Amines

[0077] Pyridines such as pyridine, conyrine, lutidine, picoline,3-pyridinol, isonicotinic acid, picolinic acid, acetylpyridine,nitropyridine, 4-pyridone, bipyridyl,2,4,6-tris(2-pyridyl)-1,3,5-triazine [TPTZ),3-(2-pyridyl)-5,6-bis(4-sulfonyl)-1,2,4-triazine [PDTS],synphenyl-2-pyridylketoxime (PPKS], and the like; quinolines such asquinoline, quinaldine, lepidine, dimethylquinoline, 8-quinolinol,2-methyl-8-quinolinol, methoxyquinoline, chloroquinoline, quinolinediol,quinaldinic acid, quinic acid, nitroquinoline, kynurine, kynurenic acid,8-acetoxyquinoline, bicinchonic acid, and the like; isoquinolines;benzoquinolines such as acridine, 9-acridone, phenanthridine,benzoquinoline, benzoisoquinoline, and the like; naphthoquinolines suchas naphthoquinoline and the like; and phenanthrolines such aso-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, basocuproin,basocuproin sulfonic acid, basophenonethroline,basophenanthrolinesulfonic acid,2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, and the like.

[0078] Further, pyrazoles such as pyrazole, 5-pyrazolone, and the like;imidazoles such as imidazole, methylimidazole, and the like;imidazolines and imidazolidines such as 2-imidazoline, imidazolidine,ethyleneurea, and the like; benzoimidazoles such as benzoimidazole andthe like; diazines such as diazine, pyrimidine, pyrazine, and the like;hydropyrimidines such as uracyl, thymine, and the like; piperazines suchas piperazine, and the like; benzodiazines and dibenzodiazines such ascinnoline, phenazine, and the like; triazines; purines; oxazoles andisooxazoles such as oxazole, 4-oxazolone, isooxazole, azoxime and thelike; oxazines such as 4H-1,4-oxazine, morpholine, and the like;thiazoles and benzothiazoles; isothiazoles; thiazines; pyrroles;pyrrolines and pyrrolidines; indoles, indolines; isoindoles; carbazoles;inindigos; porphyrins; and the like.

[0079] (B1-9) Amides and Imides

[0080] Carbamic acid, ammonium carbamate, oxamic acid, ethyl oxamate,ethyl N-nitrocarbamate, carbanilic acid, carbonylonitrile, oxanylicacid, formamide, diacetamide, hexaneamide, acrylamide, lactic acidamide, cyanoacetamide, oxamide, succinamide, salicylamide,nitrobenzamide, succinimide, maleimide, phthalic imide, and the like.

[0081] (B1-10) Anilides

[0082] Formanilides, acetanilide, hydroxyanilide, chloroanilide,methoxyacetanilide, oxanilide, and the like.

[0083] (B1-11) Urea, Thiourea and its Derivatives

[0084] Urea, N-methyl urea, N,N′-ethylidene urea, allophanic acid,glycoluric acid, oxaluric acid, buret, N-nitro urea, azodicarboneamide,thiourea, methylthiourea, dimethylthiourea, and the like.

[0085] (B1-12) Oximes

[0086] Formaldoxime, p-benzoquinonedioxime, benzaldoxime, benzyldioxime,and the like.

[0087] (B1-13) Compounds Containing a Coordinate Group Having NitrogenAtoms Bonded to Each Other

[0088] As hydrazines and hydrazides of azobenzene, azotoluene, MethylRed, azobenzene dicarboxylic acid, hydroxyazobenzene, azoxybenzene andthe like: azo and azoxy compounds including phenylhydrazine,p-bromophenylhydrazine, p-nitrophenylhydrazine, N′,-phenylacetohydrazideand the like; hyrazo compounds including hydrazobenzene,hydrazodibenzoic acid and the like; hydrazones including oxalicbis(salicylidenehydrazide), salicylaldehyde (2-carboxyphenyl)hydrazone,benzaldehyde hydrazone, acetaldehydephenylhydrazone and the like; azinesincluding benzylideneazine and the like; azides including benzoylazideand the like; diazonium salts including benzene diazonium chloride andthe like; diazo compounds including benzenediazohydroxide and the like;semicarbazides including semicarbazide and the like; andthiosemicarbazides including thiosemicarbazide and the like.

[0089] (B1-14) Others

[0090] Azides such-as ammonium azide, sodium azide and the like;nitriles such as acetonitrile and the like; amidosulfuric acid,imidodisulfuric acid, nitridetrisulfuric acid, thiocyanic acid, ammoniumthiocyanate, and the like.

[0091] In respect to a metal deposition preventive effect, when acontent of a complexing agent in a surface treatment composition isconstant, among the above Group B1, particularly amino acids such asglycine, iminocarboxylic acids such as iminodiacetic acid,nitrilotriacetic acid and ethylenediaminetetraacetic acid [EDTA], andheterocyclic polycycloamines such as 8-quinolinol and o-phenanthroline,are excellent and preferably used.

[0092] Complexing agents of Group B2 include complexing agents having atleast one atom selected from halogen, sulfur and carbon atoms as a donoratom in the molecular structure thereof. Examples of these complexingagents having such a donor atom are illustrated below, but are notespecially limited thereto. Also, salts of the following illustratedcomplexing agents include alkali metal salts or ammonium salts.

[0093] (B2-1) Complexing Agents Having a Halogen Atom as a Donor Atom

[0094] Hydrofluoric acid or its salt, hydrochloric acid or its salt,hydrogen bromide or its salt, hydrogen iodide or its salt.

[0095] (B2-2) Complexing Agents Having a Sulfur Atom as a Donor Atom

[0096] Compounds selected from thiol, sulfide or thiocarbonyl compoundsexpressed by RSH, R′₂S or R₂C═S or having at least one coordinate groupexpressed by the formula HS⁻, S² ⁻, S₂O₃ ²⁻, RS⁻, R—COS⁻, R—CSS⁻ or CS₃²⁻. In the above formulas, R is an alkyl group, and R′ is an alkyl groupor an alkenyl group, and they may be bonded to form a ring containing asulfur atom. Examples of these compounds include compounds having a HS⁻group or a S²⁻ group such as hydrogen sulfide or its salt, or sulfidesincluding sodium sulfide, ammonium sulfide and the like; compoundshaving a S₂O₃ ²⁻ group such as thiosulfuric acid or its salt; compoundshaving a RSH or RS⁻ group such as lower alkylthiol including thiol,ethanethiol and 1-propanethiol or their salts; compounds having a R—COS⁻group such as thioacetic acid, dithiooxalic acid or their salts;compounds having a R—CSS⁻ group such as ethanedibis(dithio acid),dithioacetic acid or their salts; compounds having a CS₃ ²⁻ group suchas trithiocarbonic acid or their salts or thiocarbonic acid estersincluding diethyl trithiocarbonate and the like; sulfides expressed byR′₂S such as methylsulfide, methylthioethane, diethylsulfide, vinylsulfide, benzothiophene and the like; and thiocarbonyl compoundsexpressed by R₂C═S group such as propanethion, 2,4-pentanedion and thelike.

[0097] (B2-3) Complexing Agents Having a Carbon Atom as a Donor Atom

[0098] Examples of these compounds include compounds having a NC⁻, RNCor RCC⁻ group as a coordinate group. Particular examples includecyanides such as hydrogen cyanide and ammonium cyanide, isocyanides suchas ethyl isocyanide, allylene, metal acetylide and the like.

[0099] Among the above Group B2, a complexing agent having halogen as adonor atom such as hydrofluoric acid and hydrochloric acid, areexcellent in respect to both metal deposition preventive effect andcost, and are preferably used.

[0100] Complexing agents of Group B3 include complexing agents having atleast one oxygen atom as a donor atom in the molecular structurethereof, but not having a carbonyl group and a carboxyl group and nothaving any one nitrogen, halogen, sulfur and carbon atoms as a donoratom. Examples of these complexing agents are illustrated below, but arenot especially limited thereto. The following illustrated acids such assulfonic acid and oxo acid are described as an acid, but their saltssuch as alkali metal salts or ammonium salts are included therein.

[0101] (B3-1) Complexing Agents Having a Hydroxyl Group

[0102] Saturated alcohols such as methanol, ethanol, propanol, isopropylalcohol, butanol, pentanol, hexanol, benzyl alcohol and the like;unsaturated alcohols such as allyl alcohol, methyl vinyl carbinol andthe like polyhydric alcohols such as ethylene glycol, glycerine and thelike; phenols such as phenol, catechol, Tiron and the like; and theirderivatives.

[0103] (B3-2) Complexing Agents Having a Phosphoric Acid Group

[0104] Benzene phosphonic acid and the like.

[0105] (B3-3) Complexing Agents Having a Sulfonic Acid Group

[0106] Aliphatic sulfonic acids such as methanesulfonic acid andethanesulfonic acid; and aromaticsulfonic acids such as benzenesulfonicacid, dodecylbenzenesulfonic acid and naphthalenesulfonic acid.

[0107] (B3-4) Complexing Agents Having an Ether Group

[0108] Dimethoxymethane, 1,4-dioxane, and the like.

[0109] (B3-5) Oxo Acids

[0110] Suluric acid, phosphoric acid, condensed phosphoric acid, boricacid, silicic acid, carbonic acid, nitric acid, nitrous acid, perchloricacid, chloric acid, chlorous acid, hypochlorous acid, and the like.

[0111] (B3-6) Acid Esters

[0112] Sulfuric acid esters such as ethylsulforic acid, dimethylsulforicacid and the like, carbonic acid esters such as dimethyl carbonate,diphenyl carbonate and the like, phosphoric acid esters such astrimethyl phosphate, triphenyl phosphate and the like, trimethyl borate,ethyl nitrate, ethyl nitride, and the like.

[0113] Among the above Group B3, particularly, aliphatic alcohols suchas isopropyl alcohol and oxo acids such as phosphoric acid and nitrousacid are excellent and preferably used in respect to both metaldeposition preventive effect and cost.

[0114] Complexing agents of B4 Group are carboxylic acid type complexingagents having at least one carbonyl group in the molecular structurethereof, but not having any one of nitrogen, halogen, sulfur and carbonatoms as a donor atom and not having a carbonyl group and a hydroxylgroup. Examples of Group B4 complexing agents are illustrated below, butare not especially limited thereto. Also, carboxylic acids areillustrated as a free acids, but their salts such as ammonium salts andalkali metal salts are included therein.

[0115] (B4-1) Monocarboxylic Acids

[0116] Formic acid, acetic acid, propionic acid, butyric acid,isobutyric acid, valeric acid, decanoic acid, undecanoic acid,dodecanoic acid, stearic acid, acrylic acid, crotonic acid, oleic acid,monochloroacetic acid, dichloroacetic acid, trichloroacetic acid,fluoroacetic acid, benzoic acid, methylbenzoic acid, chlorobenzoic acid,sulfocarboxylic acid, phenylacetic acid, and the like.

[0117] (B4-2) Polycarboxylic Acids

[0118] Oxalic acid, malonic acid, succinic acid, maleic acid, fumaricacid, 1,2,3-propanetricarboxylic acid, chlorosuccinic acid, phthalicacid, 1,3,5-benzenetricarboxylic acid, dichlorophthalic acid,phenylsuccinic acid, and the like.

[0119] Among the above Group B4, particularly, carboxylic acids having arelatively simple structure, i.e. C₂-C₃ aliphatic saturated carboxylicacids such as acetic acid and oxalic acid are excellent and preferablyused in respect to both metal deposition preventive effect and cost.

[0120] Complexing agents Group B5 are hydroxymono- or dicarboxylic acidtype complexing agents having at most 4 hydroxyl groups in the molecularstructure thereof, but not having any one of nitrogen, halogen, sulfurand carbon atoms as a donor atom and not having a carbonyl group. In thepresent invention, a donor atom means an atom which can provideelectrons necessary for a coordinate bond with a metal. Examples ofGroup B complexing agents are illustrated below, but are not especiallylimited thereto. The following hydroxycarboxylic acids are illustratedas a free acid, but their ammonium salts, alkali metal salts and thelike are included therein.

[0121] (B5-1) Hydroxymonocarboxylic Acids Having at Most 4 HydroxylGroups

[0122] Hydroxymonocarboxylic acids having one hydroxyl group such asglycolic acid, lactic acid, 2-hydroxybutyric acid, hydroacrylic acid,hydroxybenzoic acid, salicylic acid, sulfosalicylic acid and the like,hydroxymonocarboxylic acids having two hydroxyl groups such as glycericacid, 8,9-dihydroxystearic acid, 2,4-dihydroxybenzoic acid,protecatechuic acid and the like, and hydroxymonocarboxylic acids havingthree hydroxyl groups such as gallic acid and the like.

[0123] (B5-2) Hydroxydicarboxylic Acids Having at Most 4 Hydroxyl Groups

[0124] Hydroxydicarboxylic acids having one hydroxyl group such astartronic acid, malic acid, 2-hydroxybutanediacetic acid,2-hydroxydodecanediacetic acid, hydroxyphthalic acid and the like,hydroxydicarboxylic acids having two hydroxyl groups such as tartaricacid, 3,4-dihydroxyphthalic acid and the like, and hydroxydicarboxylicacids having four hydroxyl groups such as tetrahydroxysuccinic acid andthe like.

[0125] Among the above Group B5, particularly, hydroxydicarboxylic acidsor hydroxymonocarboxylic acids having at most 2 hydroxyl groups, such astartaric acid salicylic acid, sulfosalicylic acid and the like areexcellent and preferably used in respect to metal deposition preventiveeffect, chemical stability and cost.

[0126] On the other hand, hydroxycarboxylic acids having at least 3carboxyl groups such as citric acid do not achieve a satisfactorilymetal deposition preventive effect, and hydroxycarboxylic acids havingat least 5 hydroxyl groups such as gluconic acid, galactonic acid andthe like are not preferable since they are generally poor in chemicalstability and do not achieve a stable metal deposition preventiveeffect.

[0127] Further, a metal deposition preventive effect is related to thepositions of a hydroxyl group and a carboxyl group in a molecule and itis preferable that he two groups are bonded to carbon atoms closelypositioned.

[0128] Complexing agents of Group B6 include complexing agents having atleast one carbonyl group in the molecular structure thereof, but nothaving any one of nitrogen, halogen, sulfur and carbon atoms as a donoratom in the molecular structure thereof. Examples of these complexingagents in the present invention are illustrated below, but are notespecially limited thereto.

[0129] (B6-1) Aliphatic Aldehydes

[0130] Formaldehyde, acetaldehyde, propionaldehyde, isobutylaldehyde,acrylaldehyde, crotonaldehyde, chloroacetaldehyde, dichloroacetaldehyde,butylchloral, hydroxyacetaldehyde, lactaldehyde, D-glycerinaldehyde,formal, acetal, dichloroacetal, and the like.

[0131] (B6-2) Aliphatic Ketones

[0132] Acetone, ethyl methyl ketone, 2-methylpentanone, 3-pentanone,3-methyl-2-butanone, 4-methyl-2-pentanone, pinacolin, 2-heptanone,3-heptanone, 4-heptanone, 6-methyl-heptahnone, diisobutyl ketone,di-tert-butyl ketone, dihexyl ketone, methyl vinyl ketone, allylacetone,l-chloro-2-propanone, 1,1-dichloro-2-propanone, hydroxyacetone,dihydroxyacetone, and the like.

[0133] (B6-3) Polyoxo Compounds

[0134] Di-, and poly-aldehydes such as glyoxal, malonaldehyde,succinealdehyde, and the like, di-, and poly-ketones such as diacetyl,acetylacetone, acetonylacetone, diacetylacetone, and the like, andketoaldehydes such as pyruvine aldehyde, 4-oxopentanal, and the like.

[0135] (B6-4) Ketenes

[0136] Ketene, dimethylketene, and the like.

[0137] (B6-5) Ketocarboxylic Acids and Aldehydecarboxylic Acids

[0138] 4,4,4-trifluoro-1-phenyl-1,3-butanedione,2,2,6,6-tetramethyl-3,5-heptanedione, pyruvic acid, malonealdehyde acid,acetacetic acid, glyoxlic acid, mesooxalic acid, oxalacetic acid,oxaloglutaric acid, and the like.

[0139] (B6-6) Aromatic Aldehydes and Aromatic Ketones

[0140] Benzaldehyde, tolualdehyde, phenylacetaldehyde, cinnamaldehyde,terephthalaldehyder protocatecaldehyde, acetophenone,methylacetophenone, benzophenone, chloroacetophenone,dihydroxybenzophenone, phenylglyoxal, and the like.

[0141] (B6-7) Quinones

[0142] o-benzoquinone, p-benzoquinone, naphthoquinone, quinhydrone,2,6-dichloro-p-benzoquinone, 2,5-dihydroxy-p-benzoquinone,tetrahydroxy-p-benzoquinone, 2,3-hydroxy-1,4-naphthoquinone, and thelike

[0143] (B6-8) Tropolones

[0144] Tropolone, 6-isopropyltropolone, and the like.

[0145] The second invention of the present invention resides in that asatisfactory metal deposition preventive effect can be achieved even byonly one kind of complexing agent when the complexing agent to be addedto a liquid medium is ethylenediaminediorthohydroxyphenylacetic acid[EDDHA], 2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-⁴-naphthalenesulfonicacid [Carmagite], diammonium4,4′-bis(3,4-dihydroxyphenylazo)-2,2′-stilbenedisulfonate [Stilbazo],Pyrocatechol Violet [PV], o,o′-dihydroxyazobenzene,1′2-dihydroxy-5-nitro-1,2′-azonaphthalene-4-sulfonic acid [EriochromeBlack T] or N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid[HBED].

[0146] An amount of a complexing agent to be added as a metal depositionpreventive can not be simply determined since the amount added isdepending on the kind and amount of a metal impurity in a liquid medium,the deposition of which is prevented, and a cleaning level demanded fora substrate surface, but the total amount to be added in a surfacetreatment composition is generally from 10⁻⁷ to 2 wt %, preferably from10⁻⁶ to 0.5 wt %, more preferably from 10⁻⁶ to 0.1 wt %. If the aboveamount is too small, the aimed metal deposition preventive effect of thepresent invention is hardly achieved. On the other hand, if-the aboveamount is too large, the aimed effect can not be achieved any furtherand there is a fear that the complexing agent as a metal depositionpreventive tends to be unfavorably deposited on a substrate surface.

[0147] Examples of a liquid medium used as the main component for asurface treatment composition of the present invention include generallywater, electrolyzed ionic water, an organic solvent or an aqueoussolution having an acid, an alkali, an oxidizing agent, a reducingagent, a surfactant or the like dissolved, or their mixture solutions.Particularly when an alkaline aqueous solution or a dilute hydrofluoricacid solution is used for cleaning or etching a semiconductor substrate,metal impurities in the solution are very easily deposited on asubstrate surface, and therefore in such cases, it is preferable to usethese solutions by adding a complexing agent in accordance with thepresent invention.

[0148] In the present invention, the alkaline aqueous solution meansgenerally an aqueous solution having a pH value of higher than 7.Examples of an alkaline component in this aqueous solution are notespecially limited, but typically include ammonia. Also, other usableexamples include alkali metal or alkali earth metal hydroxides such assodium hydroxide, potassium hydroxide and calcium hydroxide, alkalinesalts such as sodium hydrogen carbonate and ammonium hydrogen carbonate,or quaternary ammonium salt hydroxides such as tetramethylammoniumhydroxide (TMAM), trimethyl-2-hydroxyethylammonium hydroxide andcholine, and the like. These alkalis may be added in a mixture of two ormore, and the total concentration of the total solution of surfacetreatment composition is adjusted to from 0.01 to 30 wt %. Also, alkalielectrolyzed ionic water obtained by electrolysis of water is preferablyused. Further, to such an alkaline aqueous solution, an oxidizing agentsuch as hydrogen peroxide may be optionally added. In a cleaning step ofsemiconductor wafer, when cleaning bare silicon (having no oxidizedfilm), it is possible to control etching or surface-roughening of thewafer by incorporating an oxidizing agent. When hydrogen peroxide isincorporated into the alkaline aqueous solution of the presentinvention, the hydrogen peroxide concentration in the total solution ofsurface treatment composition is generally adjusted within theconcentration range of from 0.01 to 30 wt %. When an oxidizing agent isused, the oxidizing agent concentration is preferably adjusted to from 1ppm by weight to 3 wt %. If the amount of the oxidizing agent is toolarge, a complexing agent is decomposed, and the stability of thesurface treatment composition tends to become poor. Particularly, whenhydrogen peroxide is used as the oxidizing agent, the hydrogen peroxideconcentration is preferably from 100 ppm by weight to 3 wt %.

[0149] Method for blending the complexing agent of the present inventionwith a surface treatment composition is not especially limited. Thecomplexing agent may be blended previously with one component or pluralcomponents of the components constituting a surface treatmentcomposition (such as aqueous ammonia, hydrogen peroxide, water and thelike), and then these components may be mixed. Alternatively, thecomplexing agent may be blended with a mixture solution obtained aftermixing the components. Also, when acids such as phenols, amino acids,iminocarboxylic acids and the like, are added, these acids may be addedin the form of an acid or they may be added in the form of a salt suchas an ammonium salt.

[0150] In the case of SC-1 cleaning, surface treatment is carried outwith a composition of (ammonia+hydrogen peroxide+water+metal depositionpreventive), but when the surface treatment composition is used for along time, ammonia is evaporated and the metal deposition preventive isgradually decomposed, thereby degrading the metal deposition preventiveeffect. Therefore, when the evaporated ammonia content is supplied, thesupplement is conducted preferably with an aqueous ammonia containing ametal deposition preventive in an amount of from 10⁻⁷ to 5 wt %,preferably from 10⁻⁶ to 1 wt %.

[0151] The surface treatment composition of the present invention isused for surface treatment operations including cleaning, etching,polishing, film-forming and the like, for substrates such assemiconductor, metal, glass, ceramics, plastic, magnetic material,superconductor and the like, the metal impurity contamination of whichbecomes troublesome. The present invention is preferably appliedparticularly to cleaning or etching of a semiconductor substrate, thesurface of which is demanded to be highly clean. Among the cleaningoperations of semiconductor substrate, when the present invention isapplied particularly to alkali cleaning with a cleaning solutioncomprising (ammonia+hydrogen peroxide+water), the problem of saidcleaning method, i.e. the problem of metal impurity deposition on asubstrate can be solved, and by this cleaning, there can besatisfactorily provided a highly clean substrate surface without beingcontaminated with particles, organic materials and metals.

[0152] The reason why the surface treatment composition of the presentinvention achieves a very satisfactory effect of preventing depositionof metal impurities, is not clear up to now, but it is considered thatsome mixing effect is achieved and some stable water-soluble metalcomplex is effectively formed between metal ions and specific two ormore complexing agents added.

[0153] When the surface treatment composition of the present inventionis used as a cleaning solution for cleaning a substrate, a method ofbringing the cleaning solution directly into contact with the substrateemployed. Examples of such a cleaning method include dipping typecleaning wherein a substrate is dipped in the cleaning solution in acleaning tank, spraying type cleaning wherein the cleaning solution issprayed on a substrate, spinning type cleaning wherein the cleaningsolution is dropped on a substrate rotated at a high speed, and thelike. In the present invention, among the above-mentioned cleaningmethods, a suitable method is employed depending on an object, but thedipping type cleaning method is preferable. The cleaning is carried outfor a suitable time, preferably from 10 seconds to 30 minutes, morepreferably from 30 seconds to 15 minutes. If the cleaning time is tooshort, the cleaning effect is not satisfactory. On the other hand, ifthe cleaning time is too long, it is meaningless since the throughputbecomes poor and the cleaning effect is not raised any further. Thecleaning may be carried out at normal temperature, but may be carriedout at a heated temperature to improve the cleaning effect. Also, thecleaning may be carried out in combination with a cleaning methodemploying a physical force. Examples of the cleaning method employing aphysical force include ultrasonic cleaning, mechanical cleaningemploying a cleaning brush, and the like.

[0154] In the present invention, in the preparation of a surfacetreatment composition, a complexing agent sometimes becomes a metalcontamination source. An ordinary reagent for the complexing agentcontains metal impurities such as Fe in an amount of from several toseveral thousands ppm. These metal impurities are present as a stablecomplex with the complexing agent at the initial stage, but when thecomplexing agent is used as a surface treatment solution for a longtime, the complexing agent is decomposed and metals become free and aredeposited on the substrate surface. Therefore, the content of at leastone metal element of Fe, Al and Zn in the complexing agent to be used ispreferably at most 5 ppm, and it is particularly preferable that the Fecontent is at most 5 ppm, the Al content is at most 2 ppm and the Zncontent is at most 2 ppm. In order to obtain such a complexing agent,when the complexing agent to be used is EDDHA, EDDHA is purified bydissolving EDDHA or its salt in an acidic or alkaline solution, removinginsoluble impurities by filtration, precipitating a crystal of EDDHA byneutralization and finally separating the crystal from the solution.

BEST MODE FOR CARRYING OUT THE INVENTION

[0155] Now, the present invention will be described in further detailwith reference to Examples. However, it should be understood that thepresent invention is not limited to such specific Examples within thescope of the subject matter of the present invention.

EXAMPLES 1 TO 8 (USE OF SINGLE COMPLEXING AGENT) AND COMPARATIVEEXAMPLES 1 TO 3

[0156] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 0.25:1:5, and to the aqueous solventthus obtained, was added a predetermined amount of each complexing agentshown in the following Table 1 as a metal deposition preventive toprepare a surface treatment composition. The amount of the complexingagent added was expressed by wt %, and the name of the complexing agentwas expressed by the above-mentioned common name. Comparative Exampleswere prepared respectively by adding ethylenediamine tetrakis(methylsulfonic acid) (common name: EDTPO) disclosed in JP-A-5-275405 asa complexing agent; by adding oxalic bis(salicylidenehydrazide)disclosed in JP-A-6-163496 as a complexing agent; or by adding nocomplexing agent.

[0157] To each of the surface treatment solutions, was added 10 ppb ofeach of Al and Fe (by using chlorides), and a clean silicon wafer (ptype, CZ, plane orientation (100)) was dipped for 10 minutes in each ofthe surface treatment solutions. During dipping, a liquid temperature ofeach surface treatment solution was raised and maintained at 40-50° C.After dipping, each silicon wafer was overflow-rinsed with ultra-purewater for 10 minutes, and was dried with nitrogen blow to determine Aland Fe deposited on the wafer surface. Al and Fe deposited on thesilicon wafer were recovered with a mixture solution of 0.1 wt % ofhydrofluoric acid and 1 wt % of hydrogen peroxide, and the metal amountswere measured by flameless atomic absorption spectrometry and wereconverted into a substrate surface concentration (atoms/cm²). Theresults are shown in the following Table 1. TABLE 1 Metal deposit Addedamount Metal deposition amount (×10¹⁰ atoms/cm²) preventive (wt %) Al FeExample 1 EDDHA 0.01 28 <6 Example 2 EDDHA 0.1 27 <6 Example 3 Carmagite0.1 35 <6 Example 4 Stilbazo 0.1 80 <6 Example 5 PV 0.1 84 <6 Example 6o,o′- 0.1 89 <6 dihydroxyazobezene Example 7 Eriochrome Black T 0.1 110<6 Example 8 HBED 0.1 120 <6 Comparative none 0 1800 200 Example 1Comparative EDTPO 0.1 330 <6 Example 2 Comparative Oxalic 0.1 1700 <6Example 3 bis(salicylidene- hydrazide)

EXAMPLES 9 TO 23 (COMBINATION USE OF A GROUP AND B1 GROUP) ANDCOMPARATIVE EXAMPLES 4 TO 15

[0158] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 0.25:1:5, the mixture solution thusobtained was used as the main component for forming an aqueous solvent.To the aqueous solvent thus formed, was added a predetermined amount ofat least 2 specific complexing agents of the present invention disclosedin Table 1 to prepare a surface treatment composition of the presentinvention. Comparative Examples were prepared respectively by adding oneof the complexing agents used in Examples; by adding catechol, Tiron or(catechol+citric acid) disclosed in JP-A-3-219000 as a complexing agent;by adding EDPPO (ethylenediaminetetrakis(methylsulfonic acid)) disclosedin JP-A-5-275405 as a complexing agent; by adding oxalic bis(salicylidenehydrazide) disclosed in JP-A-6-163495 as a complexingagent; or adding no complexing agent. However, it should be noted thatComparative Example 4 is the same as Comparative Example 1; thatComparative Example 5 is the same as Example 1; that Comparative Example6 is the same as Example 2; and that Comparative Example 13 is the sameas Comparative Example 3.

[0159] To the surface treatment solutions thus prepared, were added 10ppb of each of Al and Fe (by using chlorides), and a clean silicon wafer(p type, CZ, plane orientation (100)) was dipped for 10 minutes in eachof the surface treatment solutions. During dipping, a liquid temperatureof each surface treatment solution was raised and maintained at 40-50°C. After dipping, the silicon wafer was overflow-rinsed with ultra-purewater for 10 minutes and was then dried by nitrogen blow to determine Aland Fe deposited on the wafer surface. Al and Fe deposited on the waferwere recovered with a mixture solution of 0.1 wt % of hydrofluoric acidand 1 wt % of hydrogen peroxide, and the metal amounts were measured byflameless atomic absorption spectrometry and were converted into asubstrate surface concentration (atoms/cm²). The results are shown inthe following Table 2. TABLE 2 Metal deposit Metal deposition preventiveamount (×10¹⁰ Example (added amount/wt %) atoms/cm²) No. A Group BlGroup Al Fe Example 9 EDDHA (0.01) 8-xylenol (0.01) <9 <6 10 EDDHA(0.01) glycine (0.01) <9 <6 11 EDDHA (0.01) o-phenanthroline (0.01) <9<6 12 catechol (0.01) 8-xylenol (0.01) <9 <6 13 Tiron (0.01) 8-xylenol(0.01) <9 <6 14 Tiron (0.01) o-phenanthroline (0.01) <9 <6 15 Tiron(0.01) glycine (0.01) <9 <6 16 Tiron (0.01) iminodiacetic acid (0.01) <9<6 17 Tiron (0.01) nitrolotriacetic acid (0.01) <9 <6 18 Tiron (0.01)EDTA (0.01) <9 <6 19 Tiron (0.01) ethylenediamine (0.01) 40 <6 20 Tiron(0.01) triethanolamine (0.01) 44 <6 21 Tiron (0.01) oxalicbis(salicylidene- <9 <6 hydrazide) (0.01) 22 Tiron (0.01) sodium azide(0.01) 44 <6 23 Tiron (0.01) acetonitrile (0.01) 18 <6 Metal depositamount (×10¹⁰ Metal deposition preventive atoms/cm²) Example No. (addedamount/wt %) Al Fe Compara- tive Example 4 none 1800 200 5 EDDHA (0.01)28 <6 6 EDDHA (0.1) 27 <6 7 catechol (0.01) 330 <6 8 Tiron (0.01) 300 <69 8-xylenol (0.01) 1700 77 10 8-xylenol (0.1) 130 <6 11 o-phenanthroline(0.1) 1800 40 12 EDTA (0.01) 1700 51 13 EDTPO (0.1) 330 <6 14 oxalicbis(salicylidenehydrazide) (0.1) 1700 <6 15 catechol (0.01) + citricacid (0.01) 300 <6

EXAMPLES 24 TO 28 (COMBINATION USE OF A GROUP AND B3 GROUP) ANDCOMPARATIVE EXAMPLE 16

[0160] The same procedure as in Example 9was repeated, except thatcomplexing agents shown in the following Table 3 were used. The resultsare shown in the following Table 3. TABLE 3 Metal deposition preventiveMetal deposit amount (added amount/wt %) (×10¹⁰ atoms/cm²) Example No. AGroup B2 Group Al Fe Example 24 EDDHA (0.01) HF (0.01) <9 <6 25 EDDHA(0.01) HCl (0.01) <9 <6 26 Tiron (0.01) HF (0.01) 35 <6 27 Tiron (0.01)HCl (0.01) 35 <6 28 Tiron (0.01) benzothiophene 71 <6 Comparative HF(0.1) 1100 1000 Example 16

EXAMPLES 29 TO 39 (COMBINATION USE OF A GROUP AND B3 GROUP)

[0161] The same procedure as in Example 9 was repeated, except thatcomplexing agents shown in the following Table 4 were used. The resultsare shown in the following Table 4. TABLE 4 Metal deposition preventiveMetal deposit amount Example (added amount/wt %) (×10¹⁰atoms/cm²) No. AGroup B3 Group Al Fe Example 29 EDDHA (0.01) isopropyl alcohol <9 <6(0.01) 30 EDDHA (0.01) phosphoric acid <9 <6 (0.01) 31 Tiron (0.01)isopropyl alcohol 27 <6 (0.01) 32 Tiron (0.01) catechol 27 <6 (0.01) 33Tiron (0.01) 1,4-dioxane 27 <6 (0.01) 34 Tiron (0.01) potassium sulfate27 <6 (0.01) 35 Tiron (0.01) potassium nitrite 18 <6 (0.01) 36 Tiron(0.01) phosphoric acid 25 <6 (0.01) 37 Tiron (0.01) tripolyphosphoric 70<6 acid (0.01) 38 Tiron (0.01) perchloric acid 53 <6 (0.01) 39 Tiron(0.01) potassium carbonate 53 <6 (0.01)

EXAMPLES 40 TO 44 (COMBINATION USE OF A GROUP AND B4 GROUP) ANDCOMPARATIVE EXAMPLE 17

[0162] The same procedure as in Example 9 was repeated, except thatcomplexing agents shown in the following Table 5 were used. The resultsare shown in the following Table 5. TABLE 5 Metal deposition preventiveMetal deposit amount Example (added amount/wt %) (×10¹⁰ atoms/cm²) No. AGroup B2 Group Al Fe Example 40 EDDHA (0.01) acetic acid (0.01) <9 <6 41Tiron (0.01) acetic acid (0.01) <9 <6 42 Tiron (0.01) oxalic acid (0.01)27 <6 43 Tiron (0.01) malonic acid (0.01) 27 <6 44 Tiron (0.01) oxalicacid (0.05) + <9 <6 TMAH (0.05) Comparative Tiron (0.01) + TMAH (0.01)71 <6 Example 17

EXAMPLES 45 TO 49 (COMBINATION USE OF A GROUP AND B5 GROUP) ANDCOMPARATIVE EXAMPLES 18 TO 19

[0163] The same procedure as in Example 9 was repeated, except thatcomplexing agents shown in the following Table 6 were used. The resultsare shown in the following Table 6. Metal deposition preventive Metaldeposit amount Example (added amount/wt %) (×10¹⁰ atoms/cm²) No. A GroupB5 Group Al Fe Example 45 EDDHA (0.01) tartaric acid <9 <6 (0.01) 46catechol (0.01) tartaric acid 50 <6 (0.01) 47 Tiron (0.01) tartaric acid27 <6 (0.01) 48 Tiron (0.01) salicylic acid 18 <6 (0.01) 49 Tiron (0.01)sulfosalicyclic 27 <6 acid (0.01) Compara- tive Example 18 tartaric acid(0.1) 910 190 19 catechol (0.01) + gluconic 270 <6 acid (0.01)

EXAMPLES 50 TO 51 (COMBINATION USE OF A2 GROUP AND B6 GROUP)

[0164] The same procedure as in Example 9 was repeated, except thatcomplexing agents shown in the following Table 7 were used. The resultsare shown in the following Table 7. TABLE 7 Metal deposit Metaldeposition preventive amount Example (added amount/wt %) (×10¹⁰atoms/cm²) No. A2 Group B6 Group Al Fe 50 EDDHA (0.01) acetylacetone(0.01) <9 <6 51 Tiron (0.01) acetylacetone (0.01) <9 <6

EXAMPLES 52 TO 57 AND COMPARATIVE EXAMPLES 20 TO 24

[0165] 100 ppm of EDDHA was added as a metal deposition preventive to amixture of aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) andwater in a volume ratio of X:Y:Z to form an aqueous solvent containingthe above obtained mixture solution as the main component, thetemperature of which was raised and maintained at 40-50° C. to prepare asurface treatment composition.

[0166] The surface treatment solution thus prepared was allowed to standfor a predetermined time, and 1 ppb of each of Al and Fe (by usingchlorides) was added therein and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped for 10 minutes. The dipped wafer wasoverflow-rinsed with ultra-pure water for 10 minutes and was dried bynitrogen blow to determine Al and Fe deposited on the wafer surface. Aland Fe deposited on the silicon wafer were recovered with a mixturesolution of 0.1 wt % of hydrofluoric acid and 1 wt % of hydrogenperoxide, and the metal amounts were measured by flameless atomicabsorption spectrometry and were converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table8. TABLE 8 Volume ratio (values Time in parentheses () allowed Metaldeposit indicate wt %) to amount (×10¹⁰ NH₄OH H₂O₂ H₂O stand atoms/cm²)X Y Z (min) Al Fe Example 52 0.5(1.2) 1.0(2.5) 11 120 42 <6 Example 530.5(1.2) 0.1(0.25) 11.9 120 32 <6 Example 54 0.2(0.05) 1.0(2.7) 10 12024 <6 Example 55 1.0(2.5) 1.0(2.6) 10 120 53 <6 Example 56 0.5(1.3)1.0(2.7) 10 120 38 <6 Example 57 0.1(0.3) 0.2(0.5) 10 120 12 <6Comparative 0.5(1.2) 2.0(5.0) 10 0 27 <6 Example 20 Comparative 0.5(1.2)2.0(5.0) 10 120 180 <6 Example 21 Comparative 0.5(1.2) 2.0(5.0) 10 240580 52 Example 22 Comparative 0.5(1.2) 12(30) 0 120 850 70 Example 23Comparative 2.0(4.3) 2.0(4.4) 10 120 690 43 Example 24

[0167] As shown in Table 8, when an oxidizing agent concentration is atmost 3 wt %, a metal deposition preventive effect on a metal surface ismaintained even after allowing to stand for a long time.

EXAMPLE 58

[0168] The same procedure as in Example 57 was repeated, except that thetemperature was maintained at 70° C. After allowing to stand for 2hours, a metal deposition amount on a substrate was Al=18, Fe<6atoms/cm². Thus, a metal deposition preventive performance wasmaintained.

EXAMPLES 59 TO 60 AND COMPARATIVE EXAMPLES 25 TO 26

[0169] 1,000 ppm of Tiron was added as a metal deposition preventive toa mixture of aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) andwater in a volume ratio of X:Y:Z to form an aqueous solvent containingthe above obtained mixture solution as the main component, thetemperature of which was maintained at 40-50° C. to prepare a surfacetreatment composition.

[0170] After allowing the above prepared surface treatment solution tostand for a predetermined time, 1 ppb of each of Al and Fe (by usingchlorides) was added thereto and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped therein for 10 minutes. The dippedwafer was overflow-rinsed with pure water for 10 minutes, and was thendried by nitrogen blow to determine Al and Fe deposited on the wafersurface. Al and Fe deposited on the silicon wafer were recovered by amixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % of hydrogenperoxide, and the metal amounts were measured by flameless atomicabsorption spectrometry, and were converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table9. TABLE 9 Volume ratio (values Time in parentheses () allowed Metaldeposit indicate wt %) to amount (×10¹⁰ NH₄OH H₂O₂ H₂O stand atoms/cm²)X Y Z (min) Al Fe Example 59 0.2(0.05) 1.0(2.7) 10 0 70 <6 Example 600.2(0.05) 1.0(2.7) 10 120 80 <6 Comparative 0.5(1.2) 2.0(5.0) 10 0 84 <6Example 25 Comparative 0.5(1.2) 2.0(5.0) 10 120 520 <6 Example 26

[0171] As shown in Table 9, even if EDDHA as an organic complexing agentwas replaced by Tiron, when an oxidizing agent concentration was at most3 wt %, a metal deposition preventive effect on a substrate surface wasmaintained even after allowing to stand for a long time.

EXAMPLE 61 TO 62 AND COMPARATIVE EXAMPLES 27 TO 28

[0172] 10 ppm of EDDHA and 10 ppm of o-phenanthroline were added asmetal deposition preventives to a mixture of aqueous ammonia (30 wt %),hydrogen peroxide (31 wt %) and water in a volume ratio of X:Y:Z to forman aqueous solvent containing the above mixture solution as the maincomponent, the temperature of which was maintained at 40-50° C. toprepare a surface treatment composition.

[0173] After allowing the above prepared surface treatment solution tostand for a predetermined time, 1 ppb of each of Al and Fe (by usingchlorides) was added thereto, and a clean silicon wafer (p type, CZ,plane orientation (100)) was dipped therein for 10 minutes. The dippedwafer was overflow-rinsed with ultra-pure water for 10 minutes and wasthen dried by nitrogen blow to determine Al and Fe deposited on thewafer surface. Al and Fe deposited on the silicon wafer were recoveredby a mixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % ofhydrogen peroxide, and the metal amounts were measured by flamelessatomic absorption spectrometry and were converted into a substratesurface concentration (atoms/cm²). The results are shown in thefollowing Table 10. TABLE 10 Volume ratio (values Time in parentheses ()allowed Metal deposit indicate wt %) to amount NH₄OH H₂O₂ H₂O stand(×10¹⁰ atoms/cm²) X Y Z (min) Al Fe Example 61 0.2 1.0(2.7) 10 0 <9 <6(0.05) Example 62 0.2 1.0(2.7) 10 120 <9 <6 (0.05) Comparative 0.5(1.2)2.0(5.0) 10 0 <9 <6 Example 27 Comparative 0.5(1.2) 2.0(5.0) 10 120 220<6 Example 28

EXAMPLES 63 TO 64 AND COMPARATIVE EXAMPLE 29

[0174] An aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) andwater were mixed in a ratio of 1:1:10, and the mixture solution thusobtained was used as the main component for forming an aqueous solvent.To the aqueous solvent, was added a predetermined amount of each ofcomplexing agents of the present invention shown in the following Table11 as a metal deposition preventive to prepare a surface treatmentcomposition of the present invention. Comparative Example was preparedby adding no complexing agent to the aqueous solvent.

[0175] A silicon wafer (p type, CZ, plane orientation (100)), thesurface of which was contaminated with a metal, was dipped in the aboveprepared surface treatment solution for 10 minutes to clean the metalcontamination. During dipping, a liquid temperature of the surfacetreatment solution was raised and maintained at 40-50° C. After dipping,the silicon wafer was overflow-rinsed with ultra-pure water for 10minutes, and was then dried by nitrogen blow to determine a metal on thewafer surface. The metal on the silicon wafer surface was recovered witha mixture solution of 0.1 wt % of hydrofluoric acid and 1 wt % ofhydrogen peroxide, and the metal amount was measured by flameless atomicabsorption spectrometry and was converted into a substrate surfaceconcentration (atoms/cm²). The results are shown in the following Table11. TABLE 11 Metal deposit Metal deposition preventive amount (addedamount/wt %) (× 10¹⁰atoms/cm²) Example No. A Group B Group Al Fe CaBefore washing — 3500 1100 350 Example 63 EDDHA (0.01) o-phen- <9 <6 <4anthroline (0.005) Example 64 EDDHA (0.01) acetic acid <9 <6 <4 (0.05)Comparative none 790 990 120 Example 29

[0176] As shown in Table 11, when the substrate is treated with thesurface treatment solution of the present invention, metal depositionfrom the solution onto the substrate surface can be prevented, and metalcontamination can be removed when the substrate surface is contaminatedwith a metal.

EXAMPLE 65 AND COMPARATIVE EXAMPLES 30 TO 32

[0177] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added a predetermined amount of a complexing agent shownin the following Table 12 as a metal deposition preventive to prepare asurface treatment composition of the present invention. The amount ofthe complexing agent added was expressed by a weight ratio (ppm) to theaqueous solvent. Comparative Example was made without adding acomplexing agent. The total volume of the surface treatment compositionwas 2.8 l and was placed in a quartz tank with no lid having a capacityof 6 l. A temperature of the solution was raised and maintained at40-50° C.

[0178] The surface treatment solution thus prepared was allowed to standat 40-50° C. for such a predetermined time as shown in the followingTable 12. When allowing to stand, the ammonia content evaporated wassupplied with aqueous ammonia (30 wt %) containing a predeterminedamount of a complexing agent shown in the following Table 12. The amountof the complexing agent added in this case was expressed by a weightratio (ppm) to the ammonia aqueous solution. The amount of the ammoniaaqueous solution supplied was 76 ml per hour. After allowing to standfor a predetermined time, 1 ppb of each of Al and Fe was added theretoand a clean silicon wafer (p type, CZ, plane orientation (100)) wasdipped therein for 10 minutes. After dipping, the wafer wasoverflow-rinsed with ultra-pure water for 10 minutes, and was then driedby nitrogen blow to determine Al and Fe deposited on the wafer surface.Al and Fe deposited on the silicon wafer were recovered with a mixturesolution of 0.1 wt % of hydrofluoric acid and 1 wt % of hydrogenperoxide, and metal amounts were measured by flameless atomic absorptionspectrometry and were converted into substrate surface concentrations(atoms/cm²). The results are shown in the following Table 12. Further,for comparison, experimental results in cases of not allowing surfacetreatment solutions to stand (case of adding no complexing agent:Comparative Example 30, case of adding a complexing agent: ComparativeExample 31), and experimental results in case of allowing a surfacetreatment solution to stand for 4 hours, during which evaporated ammoniacontent was supplied with aqueous ammonia containing no complexing agent(Comparative Example 32), are shown in the following Table 12. TABLE 12Metal deposit Time amount Complexing agent (added amount/ppm) allowed (×10¹⁰ in initial surface in aqueous ammonia to stand atoms/cm²) treatmentcomposition supplied (hr) Al Fe Example 65 EDDHA (100) EDDHA (1200) 4 18<6 Comparative none no supplied 0 340 75 Example 30 Comparative EDDHA(100) no supplied 0 18 <6 Example 31 Comparative EDDHA (100) Suppliedaqueous ammonia 4 310 250 Example 32 containing no additive

[0179] As shown in Table 12, when evaporated ammonia content is suppliedwith aqueous ammonia containing 1,200 ppm of EDDHA, a metal depositionpreventive effect on a substrate surface can be maintained even afterallowing the surface treatment solution to stand for a long time.

EXAMPLES 66 TO 67 AND COMPARATIVE EXAMPLES 33 TO 34

[0180] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 13 as metal deposition preventives toprepare a surface treatment composition of the present invention. Thissolution was maintained at 40-50° C. and was allowed to stand for 4hours. Thereafter, metal deposition properties on a substrate surfacewere evaluated in the same manner as in Example 65. When allowing tostand, an evaporated ammonia content was supplied with aqueous ammonia(30 wt %) containing predetermined amounts of two complexing agentsshown in Table 13. For comparison, results in case of supplying anevaporated ammonia content with aqueous ammonia containing no complexingagent are shown also in the following Table 13. All other experimentconditions were the same as those in Example 65. TABLE 13 Metal depositTime amount Complexing agent (added amount/ppm) allowed (× 10¹⁰ ininitial surface in aqueous ammonia to stand atoms/cm²) treatmentcomposition supplied (hr) Al Fe Example 66 EDDHA (20) EDDHA (240) 4 <9<6 o-phenanthroline o-phenanthroline (120) (10) Example 67 EDDHA (20)EDDHA (240) 4 <9 <6 acetic acid (10) acetic acid (120) Comparative EDDHA(20) Supplied aqueous ammonia 4 310 230 Example 33 o-phenanthrolinecontaining no additive (10) Comparative EDDHA (20) Supplied aqueousammonia 4 380 180 Example 34 acetic acid (10) containing no additive

EXAMPLES 68 TO 71 AND COMPARATIVE EXAMPLES 35 TO 37

[0181] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:2:100, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 14 as a metal deposition preventive ormetal-removing agent to prepare a surface treatment composition of thepresent invention. This solution was maintained at 35-45° C., and afterallowing the surface treatment composition to stand for 4 hours or 8hours, metal deposition properties on a substrate surface were evaluatedin the same manner as in Example 65. During allowing to stand, anevaporated ammonia content was supplied with aqueous ammonia (30 wt %)containing predetermined amounts of two complexing agents shown in thefollowing Table 14. The amount of the ammonia aqueous solution suppliedwas 17 ml per hour. For comparison, experimental results in case ofsupplying an evaporated ammonia content with aqueous ammonia containingno complexing agent are shown in the following Table 14. All otherexperimental conditions were the same as those in Example 65. TABLE 14Metal deposit Time amount Complexing agent (added amount/ppm) allowed (×10¹⁰ in initial surface in aqueous ammonia to stand atoms/cm²) treatmentcomposition supplied (hr) Al Fe Example 68 EDDHA (2) EDDHA (200) 4 <9 <6o-phenanthroline o-phenanthroline (100) (1) Example 69 EDDHA (2) EDDHA(200) 8 <9 <6 o-phenanthroline o-phenanthroline (100) (1) Example 70EDDHA (2) EDDHA (200) 4 <9 <6 acetic acid (1) acetic acid (100) Example71 Tiron (50) Tiron (5000) 4 <9 <6 o-phenanthroline o-phenanthroline(500) (5) Comparative EDDHA (2) Supplied aqueous ammonia 4 76 18 Example35 o-phenanthroline containing no additive (1) Comparative EDDHA (2)Supplied aqueous ammonia 4 90 25 Example 36 acetic acid (1) containingno additive Comparative Tiron (50) Example 37 o-phenanthroline Suppliedaqueous ammonia 4 120 45 (5) containing no additive

EXAMPLE 72 AND COMPARATIVE EXAMPLE 38

[0182] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:2:100, and to the aqueous solvent thusobtained, were added predetermined amounts of two complexing agentsshown in the following Table 15 as a metal deposition preventive ormetal-removing agent to prepare a surface treatment composition of thepresent invention. This solution was maintained at 60-70° C., and afterallowing the solution to stand for 4 hours, metal deposition propertieson a substrate surface were evaluated in the same manner as in Example63. During allowing to stand, an evaluated ammonia content was suppliedwith aqueous ammonia (30 wt %) containing predetermined amounts of twocomplexing agents shown in the following Table 15. The amount of theaqueous ammonia supplied was 32 ml per hour. For comparison,experimental results in case of supplying an evaporated ammonia contentwith aqueous ammonia containing no complexing agent are shown in thefollowing Table 15. All other experimental conditions were the same asthose in Example 65. TABLE 15 Complexing agent Metal (added amount/ppm)deposit in Time amount initial surface in aqueous allowed (× 10¹⁰treatment ammonia to stand atoms/cm²) composition supplied (hr) Al FeExample 72 EDDHA (2) EDDHA (200) 4 <9 <6 o-phenanthro- o-phenanthrolineline (1) (100) Comparative EDDHA (2) Supplied aqueous 4 180 92 Example38 o-phenanthro- ammonia line (1) containing no additive

EXAMPLE 73 AND COMPARATIVE EXAMPLES 39 TO 40

[0183] 7 wt % of nitric acid aqueous solution was added to commerciallyavailable EDDHA (CATALOG #: E4135, Lot No. 85H5041 manufactured by SIGMACHEMICAL COMPANY, USA) in an amount of 10 ml per g of EDDHA to solveEDDHA. The EDDHA nitric acid aqueous solution was filtrated by a Teflonfilter (PTFE made) having an opening diameter of 0.1 μm to removeinsoluble impurities. To the filtrate thus obtained, was added 6 wt % ofammonia aqueous solution until a pH value of the solution becomes 8,thereby precipitating a crystal of EDDHA. The EDDHA crystal was obtainedby filtrating with a filter having an opening diameter of 5 μm. Further,the crystal thus obtained was washed with pure water on the filter.

[0184] The above operation was repeated 8 times, and the EDDHA crystalthus purified was dried in a drier to obtain a highly pure EDDHA of thepresent invention.

[0185] A metal impurity amount in the EDDHA was analyzed after beingwet-decomposed in the following manner. 1 g of EDDHA was placed in aclean quartz flask, and was subjected to carbonization by heat afteradding 5 ml of sulfuric acid. Thereafter, nitric acid and aqueoushydrogen peroxide were added thereto, and the resultant EDDHA wassubjected to oxydation-decomposition while heating. The resultant EDDHAwas further heated to evaporate materials other than sulfuric acid, andwas adjusted to 50 ml with pure water. In this manner, the sample waswet-decomposed, and the metal impurity amount was analyzed by ICP-AESmethod and atomic absorption spectrometry.

[0186] Analytical values of the highly pure EDDHA obtained in the aboveoperation are shown in the following Table 16. Also, for comparison,analytical values of unpurified EDDRA (Lot NO. 85H5041: ComparativeExample 39, Lot No. 117F50221: Comparative Example 40, manufactured bySIGMA CHEMICAL COMPANY, USA) are shown in the following Table 16. TABLE16 Conventional product Highly pure (unpurified product) productComparative Comparative Element Unit Example 73 Example 39 Example 40 Alppm <5 11 6 Cr ppm <1 50 4.5 Cu ppm <1 4 4 Fe ppm <1 950 210 Mn ppm<0.25 60 4 Na ppm <0.5 1500 120 Ni ppm <2.5 80 4 Zn ppm <1 7.5 19

[0187] As shown in Table 16, conventionally commercially available EDDHAcontains metal impurities respectively in an amount of several toseveral thousands ppm, but the metal impurities can be reduced to atmost 5 ppm by the purification method of the present invention.

EXAMPLE 74

[0188] To commercially available EDDHA (CATALOG #: E4135, Lot No.117F50221: Comparative Example 40, manufactured by SIGMA CHEMICALCOMPANY, USA), was added 3 wt % of ammonia aqueous solution in an amountof 10 ml per g of EDDHA to dissolve EDDHA. This EDDHA nitric acidaqueous solution was filtrated by a Teflon filter (PTFE made) having anopening diameter of 0.1 μm to remove insoluble impurities. To thefiltrate thus obtained, was added 23 wt % of nitric acid aqueoussolution until a pH value of the solution becomes 6, therebyprecipitating EDDHA crystal. The EDDHA crystal was obtained byfiltrating with a Teflon filter (PTFE made) having an opening diameterof 5 μm. Further, the crystal thus obtained was washed with pure wateron the filter.

[0189] The above operation was repeated 7 times, and the purified EDDHAcrystal was dried in a drier to obtain highly pure EDDHA of the presentinvention. The highly pure EDDHA of the present invention was analyzedin the same manner as in Example 73, and the results are shown in thefollowing Table 17. TABLE 17 Highly pure Element Unit product Example 74Al ppm <5 Cr ppm <1 Cu ppm <1 Fe ppm <1 Mn ppm <0.25 Na ppm <0.5 Ni ppm<2.5 Zn ppm <1

EXAMPLE 75

[0190] 240 ppm of the highly pure EDDHA obtained in Example 74 was addedand dissolved in a highly pure ammonia aqueous solution (30 wt %) toobtain EDDHA-added ammonia aqueous solution of the present invention.Analytical results of metal impurities in the EDDHA-added ammoniaaqueous solution thus obtained are shown in the following Table 18.TABLE 18 Element Unit Example 75 Al ppb <1 Cr ppb <0.5 Cu ppb <0.5 Feppb <0.5 Mn ppb <0.5 Na ppb <0.5 Ni ppb <0.5 Zn ppb <0.5

[0191] As shown in Table 18, each of metal element contents can bereduced to at most 1 ppb by using the highly pure EDDHA of the presentinvention (in case that an amount of EDDHA added is 240 ppm).

EXAMPLES 76 TO 77 AND COMPARATIVE EXAMPLES 41 TO 44

[0192] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added a predetermined amount of EDDHA shown in thefollowing Table 19 to prepare a surface treatment composition of thepresent invention. The highly pure EDDHA obtained in Example 71 was usedas EDDHA. Also, for comparison, conventionally commercially availableEDDHA (CATALOG #: E4135, Lot No. 117F50221: the same as used inComparative Example 40, manufactured by SIGMA CHEMICAL COMPANY, USA) wasused as it is for Comparative Examples. Amounts of EDDHA added wereexpressed by weight ratio (ppm) to the aqueous solvent. Further, forcomparison, a comparative composition containing no EDDHA in the aqueoussolvent was prepared. The total volume amount of a surface treatmentcomposition was 2.8 l, and the composition was placed in a quartz tankwith no lid having a capacity of 6 l. A temperature of the liquid wasraised and maintained at 55-65° C.

[0193] The surface treatment solution thus prepared was allowed to standat 55-65° C. for a predetermined time. After allowing to stand for apredetermined time, 1 ppb of each of Al and Fe was added thereto, and aclean silicon wafer (p type, CZ, plane orientation (100)) was dippedtherein for 10 minutes. After dipping, the wafer was overflow-rinsedwith ultra-pure water for 10 minutes, and was then dried by nitrogenblow to determine Al and Fe deposited on the wafer surface. Al and Fedeposited on the silicon wafer were recovered by a mixture solution of0.1 wt % of hydrofluoric acid and 1 wt % of hydrogen peroxide, and themetal amounts were measured by flameless atomic absorption spectrometryand were converted into substrate surface concentrations (atoms/cm²).The results are shown in the following Table 19. Further, forcomparison, experimental results in cases of not allowing surfacetreatment solutions to stand are shown in the following Table 19. TABLE19 Metal deposit Time amount allowed (× 10¹⁰ Complexing agent to standatoms/cm²) (added amount/ppm) (hr) Al Fe Example 76 highly pure EDDHA(100) 0 25 <6 Example 77 highly pure EDDHA (100) 2 50 <6 Comparativeconventional EDDHA (100) 0 25 <6 Example 41 Comparative conventionalEDDHA (100) 2 380 450 Example 42 Comparative none 0 340 85 Example 43Comparative none 2 350 80 Example 44

[0194] As shown in Table 19, when the highly pure EDDHA was used, ametal deposition preventive effect on a substrate surface was maintainedeven after a surface treatment solution was allowed to stand at 60° C.for a long time. On the other hand, when conventional EDDHA was used, adeposition preventive effect could be recognized immediately afteraddition, but the effect was lowered while using for a long time.Particularly, a deposition amount of Fe was more increased than in thecase of using no complexing agent. This is probably because a largeamount of Fe contained in the conventional EDDHA was separated fromEDDHA at the decomposition of EDDHA and was deposited on the substratesurface.

EXAMPLES 78 TO 80 AND COMPARATIVE EXAMPLES 45 TO 46

[0195] Aqueous ammonia (30 wt %), hydrogen peroxide (31 wt %) and waterwere mixed in a volume ratio of 1:1:10, and to the aqueous solvent thusobtained, was added predetermined amounts of two complexing agents shownin the following Table 20 as metal deposition preventives to prepare asurface treatment composition of the present invention. The highly pureEDDHA obtained in Example 73 was used as EDDHA. For comparison,conventional EDDHA (CATALOG #: E4135, Lot No. 117F50221: the same asused in Comparative Example 40, manufactured by SIGMA CHEMICAL COMPANY,USA) was used for Comparative Examples. An amount of each metal elementin acetic acid and o-phenanthroline was at most 1 ppm. This solution wasallowed to stand at 55-65° C. for a predetermined time, and metaldeposition properties on a substrate surface were evaluated in the samemanner as in Example 73. All other experimental conditions were the sameas those of Example 76. Experimental results are shown in the followingTable 20. TABLE 20 Metal deposit Time amount allowed (×10¹⁰ Complexingagent to stand atoms/cm²) (added amount/ppm) (hr) Al Fe Example 78highly pure EDDHA (20) 0 <9 <6 acetic acid (100) Example 79 highly pureEDDHA (20) 2 32 <6 acetic acid (100) Example 80 highly pure EDDHA (20) 240 <6 o-phenanthroline (10) Comparative conventional EDDHA (20) 0 <9 <6Example 45 acetic acid (100) Comparative conventional EDDHA (20) 2 329227 Example 46 acetic acid (100)

Industrial Applicability

[0196] The surface treatment composition of the present inventioncontaining a specific complexing agent as a metal deposition preventive,prevents a substrate surface from being contaminated with metalimpurities such as Al and Fe from the surface treatment composition, andstably provides an extremely clean substrate surface.

[0197] Particularly, when the present invention is applied to alkalicleaning of a semiconductor substrate represented by “ammonia+hydrogenperoxide+water” cleaning, a conventional problem of this cleaning methodconcerning a metal impurity deposition problem is solved, and a highlyclean substrate surface can be provided by this cleaning without beingcontaminated with particles, organic materials and metals. Thus,conventionally employed acid cleaning such as “hydrochloricacid+hydrogen peroxide+water” cleaning conducted after this cleaning canbe omitted, and it is therefore possible to largely reduce the cleaningcost, a clean room cost including an exhauster equipment and the like,thus being largely advantageous in industrial production ofsemiconductor integrated circuits.

1. A method for treating the surface of a substrate with a surfacetreatment composition, wherein the surface treatment compositioncomprises a liquid medium containing a complexing agent as a metaldeposition preventive, the complexing agent comprising at least onemember selected from the following Group A complexing agents and atleast one member selected from the group consisting of the followingGroups Bl to B6 complexing agents: Group A: complexing agents having anaromatic hydrocarbon ring in the molecular structure thereof and atleast one of an OH group and/or an O⁻ group bonded directly to a carbonatom constituting the ring; Group B1: complexing agents having at leastone nitrogen atom as a donor atom-in the molecular structure thereof;Group B2: complexing agents having at least one atom selected fromhalogen, sulfur and carbon atoms as a donor atom in the molecularstructure thereof; Group B3: complexing agents having at least oneoxygen atom as a donor atom in the molecular structure thereof, but nothaving a carbonyl group and a carboxyl group and not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom; Group B4:carboxylic acid type complexing agents having at least one carboxylgroup in the molecular structure thereof, but not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom and nothaving a carbonyl group and a hydroxyl group; Group B5: hydroxymono- ordi-carboxylic acid type complexing agents having at most 4 hydroxylgroups in the molecular structure thereof, but not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom and nothaving a carbonyl group; and Group B6: complexing agents having at leastone carbonyl group in the molecular structure thereof.
 2. The methodaccording to claim 1, wherein the Group B1 complexing agents having atleast one nitrogen atom as a donor atom, have at least one coordinategroup selected from the group consisting of an amino group, an iminogroup, a nitrilo group (tertiary nitrogen atom), a thiocyanate group, ahydroxyamino group, a hydroxyimino group, a nitro group, a nitrosogroup, a hydrazino group, a hydrazono group, a hydrazo group, an azogroup, an azoxy group, a diazonium group and an azido group.
 3. Themethod according to claim 1, wherein the Group B1 completing agents havean iminocarboxylic acid group or a heterocyclic polycyclic amino group.4. The method according to claim 1, wherein the Group B2 complexingagents having a halogen atom as a donor atom, are hydrofluoric acid,hydrochloric acid, hydrogen bromide or hydrogen iodide or their salts.5. The method according to claim 1, wherein the Group B2 complexingagents having a sulfur atom as a donor atom, have at least onecoordinate group expressed by the formula HS⁻, S²⁻, S₂O₃ ²⁻, RS⁻,R—COS⁻, R—CSS⁻ or CS₃ ²⁻, or are selected from thiol, sulfide orthiocarbonyl compounds expressed by RSH, R′₂S or R₂C═S (provided that Rin the above formulas is an alkyl group, R′ is an alkyl group or analkenyl group, and they may be connected with each other to form a ringcontaining a sulfur atom).
 6. The method according to claim 1, whereinthe Group B2 complexing agents having a carbon atom as a donor atom,have at least one coordinate group expressed by the formula NC⁻, RNC orRCC⁻ (provided that R in the formulas is an alkyl group).
 7. The methodaccording to claim 1, wherein the Group B3 complexing agents have atleast one coordinate group selected from a hydroxyl group, a phosphonicacid group, a sulfonic acid group and an ether group.
 8. The methodaccording to claim 1, wherein the Group B3 complexing agents are oxoacid or its salt or ester.
 9. The method according to claim 8, whereinthe oxo acid is sulfonic acid, phosphoric acid, condensed phosphoricacid, boric acid, silicic acid, carbonic acid, nitric acid, nitrousacid, perchloric acid, chloric acid, chlorous acid or hypochlorous acid.10. The method according to claim 1, wherein the Group B4 complexingagents are selected from C₂-C₃ saturated aliphatic mono- ordi-carboxylic acids or their salts.
 11. The method according to claim 1,wherein the Group B5 completing agents are hydroxymono- or di-carboxylicacids having one or two hydroxyl groups in the molecular structurethereof.
 12. The method according to claim 1, wherein the Group B6complexing agents do not contain any one of nitrogen, halogen, sulfurand carbon atoms as a donor atom in the molecular structure thereof. 13.The method according to claim 1, wherein the Group B6 complexing agentshave at least 2 carbonyl groups in the molecular structure thereof. 14.The method according to claim 1, wherein the Group A complexing agentshave at least two OH groups and/or O⁻ groups in the molecular structurethereof.
 15. The method according to claim 1, wherein the content of themetal deposition preventive is from 10⁻⁷ to 2 wt %.
 16. The methodaccording to claim 14, wherein the content of the metal depositionpreventive is from 10⁻⁶ to 0.5 wt %.
 17. The method according to claim1, wherein the liquid medium is an alkaline aqueous solution.
 18. Themethod according to claim 16, wherein the alkaline aqueous solutioncontains ammonia and hydrogen peroxide.
 19. A surface treatmentcomposition comprising a liquid medium containing a complexing agent asa metal deposition preventive, the complexing agent comprising at leastone member selected from the following Group A complexing agents and atleast one member selected from the group consisting of the followingGroups B1 to B6 complexing agents: Group A: complexing agents having anaromatic hydrocarbon ring in the molecular structure thereof and atleast one of an OH group and/or an O⁻ group bonded directly to a carbonatom constituting the ring; Group B1: complexing agents having at leastone nitrogen atom as a donor atom in the molecular structure thereof;Group B2: complexing agents having at least one atom selected fromhalogen, sulfur and carbon atoms as a donor atom in the molecularstructure thereof; Group B3: complexing agents having at least oneoxygen atom as a donor atom in the molecular structure thereof, but nothaving a carbonyl group and a carboxyl group and not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom; Group B4:carboxylic acid type complexing agents having at least one carboxylgroup in the molecular structure thereof, but not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom and nothaving a carbonyl group and a hydroxyl group; Group B5: hydroxymono- ordi-carboxylic acid type complexing agents having at most 4 hydroxylgroups in the molecular structure thereof, but not having any one ofnitrogen, halogen, sulfur and carbon atoms as a donor atom and nothaving a carbonyl group; and Group B6: complexing agents having at leastone carbonyl group in the molecular structure thereof.
 20. A method fortreating the surface of a substrate with a surface treatmentcomposition, the surface treatment composition contains at least onecomplexing agent selected from the group consisting ofethylenediaminediorthohydroxyphenylacetic acid,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid,diammonium 4,4′-bis(3,4-dihydroxyphenylazo)-2,2′-stilbenedisulfonate,Pyrocatechol Violet, o,o′-dihydroxyazobenzene,1′2-dihydroxy-5-nitro-1,2′-azonaphthalene-4-sulfonic acid andN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid, as a metaldeposition preventive in a liquid medium.
 21. The method according toclaim 19, wherein the metal deposition preventive is ethylenediaminediorthohydroxyphenyl acetic acid.
 22. The method according to claim 19,wherein the content of the metal deposition preventive is from 10⁻⁷ to 2wt %.
 23. The method according to claim 19, wherein the liquid medium isan alkaline aqueous solution.
 24. The method according to claim 22,wherein the alkaline aqueous solution contains ammonia and hydrogenperoxide.
 25. A surface treatment composition containing at least onecomplexing agent selected from the group consisting of ethylenediaminediorthohydroxyphenyl acetic acid,2-hydroxy-1-(2-hydroxy-5-methylphenylazo)-4-naphthalenesulfonic acid,diammonium 4,4′-bis(3,4-dihydroxyphenylazo)-2,2′-stilbenedisulfonate,Pyrocatechol Violet, o,o′-dihydroxyazobenzene,1′2-dihydroxy-5-nitro-1,2-azonaphthalene-4-sulfonic acid andN,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid, as a metaldeposition preventive in a liquid medium.
 26. The surface treatmentcomposition according to claim 24, wherein the metal depositionpreventive is ethylenediamine diorthohydroxyphenyl acetic acid.
 27. Amethod for treating the surface of a substrate with a surface treatmentcomposition, wherein the surface treatment composition is a compositioncontaining an oxidizing agent and an organic complexing agent having anOH group bonded directly to an aromatic hydrocarbon group in a liquidmedium and the concentration of the oxidizing agent is from 1 ppm to 3wt %.
 28. The method according to claim 26, wherein the organiccomplexing agent is a complexing agent having at least 2 OH groupsbonded directly to an aromatic hydrocarbon group in one molecule. 29.The method according to claim 26, wherein the liquid medium contains atleast 2 complexing agents and at least one of the complexing agents is acomplexing agent not having an OH group bonded directly to an aromatichydrocarbon group in a molecule.
 30. The method according to claim 28,wherein the complexing agent not having an OH group bonded directly toan aromatic hydrocarbon group is a complexing agent selected from thegroup consisting of Groups B1 to B6.
 31. The method according to claim26, wherein the oxidizing agent is from 100 ppm by weight to 3% byweight of hydrogen peroxide.
 32. The method according to claim 26,wherein the liquid medium contains at most 3 wt % of ammonia.
 33. Asurface treatment composition containing an oxidizing agent and anorganic complexing agent having an OH group bonded directly to anaromatic hydrocarbon group in a liquid medium, wherein the concentrationof the oxidizing agent is from 1 ppm by weight to 3% by weight.
 34. Amethod for treating the surface of a substrate with an alkaline surfacetreatment composition containing ammonia, water and an organiccomplexing agent having a cyclic structure in the molecular structurethereof and at least one of an OH group and/or an O⁻ group bonded to acarbon atom constituting the cyclic structure as a metal depositionpreventive in a liquid medium, wherein an ammonia component evaporatedduring the surface treatment is supplied with an ammonia aqueoussolution containing the organic complexing agent.
 35. The methodaccording to claim 33, wherein the concentration of ammonia is from 0.1to 35 wt % and the concentration of the organic complexing agent is from10⁻⁷ to 2 wt % in the liquid medium.
 36. The method according to claim33, wherein the liquid medium further contains hydrogen peroxide. 37.The method according to claim 35, wherein the concentration of thehydrogen peroxide is from 100 ppm by weight to 3 wt %.
 38. The methodaccording to claim 33, wherein the organic complexing agent has a cyclicstructure in the molecular structure thereof and has at least 2 OHgroups and/or O⁻ groups bonded directly to a carbon atom constitutingthe cyclic structure.
 39. The method according to claim 33, wherein theammonia aqueous solution supplied contains ammonia at a concentration offrom 0.1 to 35 wt %, an organic complexing agent at a concentration offrom 10⁻⁷ to 5 wt % and a metal impurity at a concentration of at most10⁻⁴ wt % per metal.
 40. The method according to claim 33, wherein thecomposition further contains an organic completing agent selected fromthe group consisting of the above Groups B1 to B6 as an organiccomplexing agent.
 41. A method for treating the surface of a substratewith a surface treatment composition, wherein the surface treatmentcomposition is a composition obtained by adding a highly pureethylenediaminediorthohydroxyphenylacetic acid containing at most 5 ppmof at least one metal element of Fe, Al and Zn or its ammonium salt, asa metal deposition preventive to a liquid medium.
 42. The methodaccording to claim 40, wherein the highly pureethylenediaminediorthohydroxyphenylacetic acid or its ammonium saltcontains at most 5 ppm of Fe, at most 2 ppm of Al and at most 2 ppm ofZn.
 43. A highly pure ethylenediaminediorthohydroxyphenylacetic acid orits ammonium salt, in which the content of at least one metal element ofFe, Al and Zn is at most 5 ppm.
 44. A surface treatment compositioncontaining the highly pure ethylenediamineorthohydroxyphenylacetic acidor its ammonium salt according to claim
 42. 45. The surface treatmentcomposition according to claim 43, which contains from 10⁻⁷ to 5 wt % ofethylenediaminediorthohydroxyphenylacetic acid, from 0.1 to 35 wt % ofammonia and at most 5 ppb of at least one metal element of Fe, Al andZn.
 46. A method for purifying a highly pureethylenediaminediorthohydroxyphenylacetic acid or its ammonium salt,which comprises dissolving ethylenediaminediorthohydroxyphenylaceticacid or its salt in an acidic or alkaline solution, removing insolubleimpurities by filtration, precipitating a crystal ofethylenediaminediorthohydroxyphenylacetic acid by neutralization andseparating the crystal from the solution.
 47. The method according toclaim 45, wherein the separation of the insoluble impurities byfiltration is conducted by a filter having an opening diameter of atmost 0.5 μm.